U.S. Pat. No. 5,595,509 discloses an electrical connector, an insulative housing of the electrical connector is integrally formed with a locking arm thereon. When the electrical connector and a mating connector which is mated with the electrical connector are connected, the locking arm and a corresponding locking structure of the mating connector are latched with each other, so that the electrical connector and the mating connector are locked together. When the electrical connector and the mating connector needs to be separated from each other, the locking arm is pressed down, which makes the locking arm be elastically deformed and release the latching with the locking structure of the mating connector. In such an electrical connector, if an elastic coefficient of the locking arm is designed to be too large, it is difficult to press down the locking arm, both latching and separating between the locking arm and the locking structure need more effort; if the elastic coefficient of the locking arm is designed to be too small, the locking arm will be easy to plastically deform and even damage due to excessive pressure, therefore the electrical connector is needs to be further improved.